[j-nsp] BGP/MPLS Question MX Platform

[Alexander Arseniev]

Hello,

On 03/08/2016 22:09, Dean B wrote:
> Thanks.  I think the part I'm missing is associating the IP traffic to an
> LSP and how to prevent it from just going back to IGP routing when the LSP
> fails.
There are several ways to do that.
1) use forwarding-table policy to associate BGP routes with a particular LSP
https://www.juniper.net/documentation/en_US/junos15.1/topics/reference/configuration-statement/install-nexthop-edit-policy-options.html 

This policy should have 2 terms: term 1 from community BGP-ROUTE-COMM 
then install-nexthop lsp <name>; term 2 from community BGP-ROUTE-COMM 
then next-hop discard
2/ You can deny resolution of BGP routes' nexthop via inet.0, and let it 
only use inet.3.
By default, BGP routes' nexthop is resolved via inet.3 and then, if no 
joy, via inet.0.
If You deny inet.0 usage for BGP routes' nexthop resolution, BGP routes 
will be invaldated once LSP fails.
The command is
set routing-options resolution rib inet.0 resolution-rib inet.3
3/ You also can configure static discard routes in inet.3 table to set 
all BGP routes' nexthops to discard should A-C LSP fail:
In router A: set routing-options rib inet.3 static route <router C 
loopback>/32 discard preference 8
In router C: set routing-options rib inet.3 static route <router A 
loopback>/32 discard preference 8
But - if there are MPLS VPN between A and C, and You want them continue 
using LDP, then (3) is not a good option.
With (3), A-C MPLS VPN will stop working after A-C LSP fails whereas in 
option (2) only IP traffic will stop working.


HTH
Thx
Alex